The public's attention is currently focused on DVDs as digital contents storage media that are to replace CDs. Since the DVD media have a storage capacity larger than that of conventional CD media, not only motion-picture data can be stored, but also multi-channel audio signal data, e.g., 5.1-channel audio signals, can be recorded. Reproducing such multi-channel audio signals allows the sense of being present to be created even at home, as in a movie theater.
In order for the sense of being present to be created, by reproducing such multi-channel audio signals, however, a multi-channel audio signal reproduction system such as an amplifier to drive each of loudspeakers is required along with multiple loudspeakers whose quantity exceeds two. A 5.1-channel system, for instance, would require five loudspeakers or more. Such a large quantity of the loudspeakers need to secure some extra space for their arrangement. Additionally, wiring-interconnections between the signal reproduction system and the loudspeakers become complex. Given the present circumstances, even though low-cost reproduction systems and loudspeakers become available in the market, promotion of their widespread use is unlikely to be anticipated.
This background demands, with the already-widespread two-speaker system configuration remaining unchanged, a technology to create surround sound images by reproducing the multi-channel audio signals. As an example of such technology, the methods referred as to SET1 and SET2 have been disclosed in non-Patent Document 1.
In addition, a method is proposed—by e.g., Patent Document 1—as well in which, using a pair of loudspeakers, stereophonic surround sounds are reproduced by front-side stereophonic signals, and rear-localized stereophonic rear signals—rear sounds.